# All Pairwise Comparisons among Means: Tukey's HSD Procedure (2 of 2)

Next section: Newman-Keuls
The

critical value of t

_{s }is determined
from the distribution of the studentized range. The number of means in the
experiment is used in the determination of the critical value, and this
critical value is used for all comparisons among means. Typically, the largest
mean is compared with the smallest mean first. If that difference is not significant,
no other comparisons will be significant either, so the computations for these
comparisons can be skipped.

The Tukey HSD procedure keeps the

EER
at the specified significance level. This is a great advantage. This
advantage comes at a cost, however: the Tukey HSD is less powerful
than other methods of testing all pairwise comparisons.

Next section: Newman-Keuls